This invention relates generally to the longitudinal sealing of low density polyethylene films having utility in the product packaging arts.
The longitudinal seal as used in the art is an overlapping seal of a width generally from 3/4inch to 11/4 inches. Such is in contrast to the cross seal used in packaging which generally is quite narrow and which is achieved by the known thermal hot knife process.
It has been known in the arts to achieve a longitudinal seal by various pressure and/or heat sealing methods of the prior art.
The use of a static charge in combination with pressure and/or thermal sealing means has recently been introduced by the inventor of the present application. Such usage has proven to be novel and highly useful. Recent experimentation, however, has been successfully performed which significantly improves the quality and consistency of longitudinal seals. Such is the subject matter of the present specification.
Accordingly, it is an object of the present invention to demonstrate a longitudinal sealing system which results in a higher quality seal of enhanced durability and appearance.
It is a further object of the invention to demonstrate a longitudinal sealing system which is of improved consistency from seal to seal and over long production time periods.
It is a still further object to illustrate a longitudinal sealing apparatus which may be economically constructed and used in the product sealing arts.
It is also a highly important object of the invention to demonstrate a novel method of inducing a static charge as a part of a film sealing process.
These and other objects and advantages of the invention will be apparent to those of skill in the art from the description which follows.